Cost of double extension help

[Bunches99]

We are in the process of applying for planning permission to extend our old garage 3 x 3 meters on the ground floor and build a 3 x 6.5 m extension on the first floor. So roughly 28.5 meters.

I’m on the SE Coast in kent. I know a brickie, electricians, plumbers and carpenters who are all excellent and give good prices. Which I am happy to project manage, once the build is done

Does anyone know how I budget for just the structure to be built?

there would likely need to be some
kind of steels over the existing garage, as I don’t believe the footings would be strong enough to support the 1st floor. Though the extended part would have footings for the two floors as it’s new. does that make sense?

so it’s half an extension at the bottom and a full extension on the top.

Have you had detailed plans drawn up?

Did you employ an structural engineer to do a survey on your garage and existing walls in view of building up & knocking through?
If not, your plans are worthless as building control would not sign them off without.

Not yet - still in the architect phase- but worried it’s going to be too much and thinking maybe we should he scaling back to just extending the downstairs

We’re at the stage before that. The architect is working on options. Then it goes to the surveyors and planning control.

I just wondering if our ideas are too ambitious for our budget. And wondering if we should scale them back

Your best bet is to ask the architect, they'll have a good feel for prices in your area.

We did something similar and the architect project managed it - if you do it yourself, you'll end up with delays because the plumber isn't available when you need them, and then when something goes wrong the electrician and the builder will be arguing over who's at fault rather than just fixing the problem. Much easier to get it all done under the one contract if you can.

Well have you not had ballpark estimates?
Often you can’t utilize the existing garage anyway, so be prepared for that.
I have no idea of extension costs but going from MN figures, including a new kitchen etc, anything from 40 to 75 for just a ground floor, and another 30 or so for an upstairs.

No new kitchen, it’s a den downstairs with a ensuite. And a 4th bedroom upstairs. I’m hoping my 80k budget will be enough.

my architect doesn’t project manage and doesn’t have an idea of cost sadly

I did something similar and £80k wasn't half of it I'm afraid.

Our square footage was bigger in fairness though.

If we can build over the existing garage that’s already converted to living space. It’s 28.5 square meters.

I am happy to project manage as we’ve had loads of work done with these trades people and they are all good. It has to be cheaper to do it this way and I have fair amount of experience organising them all, as I’ve renovated a few properties. And I’m an accountant.

it’s a price for the shell that I’m trying ascertain. 28.5 square meters x 2500 - would come to 71,250. Which is the estimated price given by many websites.

But I haven’t ever done a large build like this.

I have an extra 20k, so have 90 in total.

once I have plans, I can speak to a surveyor. I just wanted to know if others had an idea, whilst we wait.

Planning an extension in the north east recently, the architect advised £3kpsm as a post-COVID price for the shell.

I would get a rough price from your builder - he won't be able to give you an exact quote but he could give you an idea.

We had a 72sqm extension done in late 2022 and it cost considerably less than 2.5k per sqm. Partly because we know the builder well and he gave us a v good price but it was also a very straightforward build. Point is that every project is different. Your best bet is to talk to your builder.

Strange that the architect didn't offer a rough idea, we worked with a company called Home Tales and they were very upfront when we did our kitchen extension. It ended up coming in around 65k which was similar to their previous projects but that was only a ground floor